I recently purchased some XRCDs from Elusive Disc. One of the titles is "The Super Extended Resolution Sound of TBM". It also has a blurb about this disc being " An essential tool for gauging the performance of your audio system".
It is an interesting disc. It has some types of music I like and some I do not. The ones I found hardeset to listen to were the vocals. This disc is recorded in Japan and the the vocalists are Japanese. The phrasing and pronunciation is/was not appealing to me but was able to get through it to use the disc as designed.
There are 15 pages of notes in the liner. The notes cover how things were mic'd, drawings of the location of instruments, and what I thought most important, what to key on for each song to test your rig. For example, one cut, Star Dust, says, "The strings, though purposely placed at the background, so as not to compete with the solo piano, are soothing and silky, yet very delicate and articulate". Cymbal attack, use of brushes and imaging are all covered.
I think this disc was a good investment. It helped me gain a little more understanding and it helped me with some minor speaker positioning tweaks I needed to do. The challenging part was reading and listening at the same time which did not work! So, I took quick notes and compared them to the liner until I was familiar and aware of what they were trying to emphasize. It also gave my system a chance to reveal it's strengths and weaknesses. Again, I think it can be used as tool even if you do not like the music.